A199897 - cp's OEIS frontend

A199897 Number of -7..7 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

n	a(n)
1	1
2	15
3	85
4	799
5	5839
6	51395
7	406575
8	3500269
9	28684325
10	245319361
11	2048301005
12	17499467353
13	147731409251
14	1263413909311
15	10741266363733
16	92019265611439
17	786112365529335
18	6747253002120179
19	57843127733658007
20	497375672047480891

[1, 15, 85, 799, 5839, 51395, 406575, 3500269, 28684325, 245319361, 2048301005, 17499467353, 147731409251, 1263413909311, 10741266363733, 92019265611439, 786112365529335, 6747253002120179, 57843127733658007, 497375672047480891]

cp's OEIS Frontend

A199897 Number of -7..7 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

Table of values

List of values